Reductant Temperature Sensor Circuit Low
The reductant temperature sensor circuit is detecting a low voltage signal, indicating a problem with the SCR (Selective Catalytic Reduction) system's ability to monitor reductant fluid temperature. This code typically appears on diesel vehicles and must be addressed to prevent catalyst damage and emissions system failure.
What You Might Notice
- Reduced fuel efficiency
- Excessive black smoke from exhaust
- Diminished engine performance
- Check engine light illumination
- Limp mode activation or power reduction
Most Common Causes
- 1
Defective reductant temperature sensor
The sensor itself may have failed electrically or mechanically, causing it to send low voltage signals to the PCM. This is the most common cause of P2044.
- 2
Wiring or connector issues
Corroded, damaged, or loose connections in the sensor circuit can cause intermittent or continuous low voltage readings. Check the sensor connector and wiring harness for damage.
- 3
Open circuit in sensor wiring
A break in the wire between the sensor and PCM prevents proper signal transmission, registering as a low or missing voltage condition. This may result from rodent damage or wear.
- 4
PCM or module malfunction
Rarely, the powertrain control module itself may be faulty and unable to properly read valid sensor signals, requiring module replacement or reprogramming.
How to Diagnose It
- 1
Check Defective reductant temperature sensor — The sensor itself may have failed electrically or mechanically, causing it to send low voltage signals to the PCM. This is the most common cause of P2044.
- 2
Check Wiring or connector issues — Corroded, damaged, or loose connections in the sensor circuit can cause intermittent or continuous low voltage readings. Check the sensor connector and wiring harness for damage.
- 3
Check Open circuit in sensor wiring — A break in the wire between the sensor and PCM prevents proper signal transmission, registering as a low or missing voltage condition. This may result from rodent damage or wear.
- 4
Check PCM or module malfunction — Rarely, the powertrain control module itself may be faulty and unable to properly read valid sensor signals, requiring module replacement or reprogramming.
How to Fix It
- 1
Replace reductant temperature sensor
Remove and install a new reductant temperature sensor. Locate the sensor on the reductant (DEF) tank or supply line, disconnect the electrical connector, unscrew the old sensor, and install the new one with a new gasket if applicable.
- 2
Inspect and repair wiring and connectors
Examine the sensor wiring harness and connector for corrosion, damage, or loose pins. Clean corroded connectors with electrical contact cleaner, repair any damaged wires by splicing or replacing the harness section, and ensure all connections are fully seated.
- 3
Test power and ground circuits
Using a multimeter, verify that the sensor is receiving proper voltage (typically 5V reference) and has a good ground connection. If voltage is missing or low at the sensor connector, trace the circuit back to find breaks or damaged wires.
- 4
Reprogram or replace PCM
If all wiring and sensor tests pass, the PCM may need reprogramming or replacement. This should only be performed after all other causes have been ruled out by a qualified technician with proper diagnostic equipment.
Need a deeper diagnosis?
Search for related repair guides or browse by system.